The present invention relates to a metal laminate gasket suitable for a cylinder head gasket and so on.
Conventionally, in a metal laminate cylinder head gasket, there is a gasket having a steel plate as one of metal plates. FIG. 3 shows an example showing an area around a water hole, in which a plate 11 formed of a stainless material and a plate 12 formed of the above explained steel plate are combined. Generally, upper and lower surfaces of the steel plate are plated to form plated layers 13 for preventing rust. In the figure, numeral 14 shows a coating layer for sealing.
However, no consideration for preventing rust is made at a cut surface 12a of an edge, such as an edge of a water hole punched in the steel plate 12, in which rust and corrosion are likely to occur, because the area is very small and it takes time for processing. However, it is desirous to provide a rust preventing process at the cut surface. A specific procedure for rust preventing process must be avoided because of increasing of cost.
The basic technical feature of present invention is to provide a metal laminate gasket in which a rust and corrosion prevention process is applied to a cut surface around an edge, such as a water hole and so on, in a steel plate.
Another technical feature of the invention is to provide a metal laminate gasket, in which a rust and corrosion prevention process can be made without a specific additional process in providing the rust and corrosion preventing process at the cut surface around the edge in the steel plate.
Further objects and advantages of the invention will be apparent from the following description of the invention.